An existing design for an autothermal reforming apparatus consists of a refractory lined, cylindrical vessel with a conical top part where the burner is installed in the top of the cone. The vessel is in principle divided into two zones, the top part being used as a flame chamber where combustion takes place and where also a high velocity swirling back-mix ensures an even temperature and composition at the inlet to the next zone where the filling of reforming catalyst takes care of equilibration of the reforming gas mixture.
This design is limited in capacity, mainly by two factors:
a. The refractory lined reactor can only be built up to a certain maximum diameter (maximum regarded to be for the moment approximately 7 m).
b. If the catalyst bed does not have enough flow area, the pressure drop over the catalyst bed will lead to risk of gas passing through the refractory lining or even behind the lining so that the pressure shell is overheated and damaged. (There are numerous examples from the industry that such a risk is real.)